I am planning on adding a set of Rev 10's, powered by a Syn4 to my tower. Currently the boat is running 2 amps, 8 in-boats, 1 sub and 2 sets of tower speakers. It is configured with 2 batteries and a Blue Sea battery switch. Currently, it has no distribution block for the wiring and I think I am going to gut out the current setup and rewire. I have a few questions about how to wire though.

The plan right now is to run a 1/0 guage wire from the B + of the second battery with an inline fuse to the distribution block. 1st question. From what I understand, this fuse needs to equal the fuse total of all amps being run from the distribution block? The 2 amps I currently have in there both have 2x30amp fuses and the Syn4 runs 3x30amp fuses (could be mistaken on Syn4 since I don't have it yet). Does this mean the inline fuse needs to equal 210 amps (60+60+90)?

From the inline fuse, I will continue running the 1/0 guage to the distribution block. The distribution block will have 3 4gauge outputs. From what I understand, the distribution block should also be fused for the associated amp fuses. Therefore, I would have 2x 60 amp fuses and 1x 90amp fuse in the distribution block? From there, I would simply run 4 gauge to the power input on the amps. The negatives of the amps would run a 4 gauge back to a different distrbution block which has a 1/0 guage out to the negative of the 2nd battery. Does this distribution block need to be fused and does there need to be another inline fuse like the positive?